Grade 304 Stainless Steel has mainly a chromium and nickel content with an extremely low content of Carbon. It contains 18% chromium and 8% nickel and is also an Austenitic Stainless Steel. Grade 316 Stainless Steel contains 16% chromium and 10% Nickel as well as 2% Molybdenum and is also an austenitic Stainless Steel. The Molybdenum in the Grade 316 is added to resist corrosion such as sea salt. This Molybdenum is the main difference between Grade 304 and Grade 316. The appearance to the eye of the Grade 316 and Grade 304 is exactly the same. The only way to tell the difference is through laboratory tests. Grade 316 can cost 30% more than Grade 304 but is definitely required for coastal applications that are exposed to sea salts. The additional cost you pay upfront for the superior grade 316 will be worthwhile to ensure a shiny Stainless Steel look for years to come. If however, your application is indoors or far enough from sea salts, the grade 304 will be ideal. It is a little cheaper but will behave in the same manner as the 316 and look like new for many years to come.